Document System.Drawing OutOfMemoryException to ExternalException breaking change for .NET 10 with C# and VB examples

[Copilot]

This PR adds documentation for a breaking change in .NET 10 Preview 5 where System.Drawing's GDI+ error handling was updated to throw ExternalException instead of OutOfMemoryException for Status.OutOfMemory errors.

Changes Made

Added new breaking change document: docs/core/compatibility/windows-forms/10.0/system-drawing-outofmemory-externalexception.md

• Documents the version introduced (.NET 10 Preview 5)
• Explains previous vs new behavior with GDI+ error handling
• Provides reasoning: GDI+ often returns Status.OutOfMemory for invalid input rather than actual memory issues, causing confusion
• Includes recommended action with code examples in both C# and VB.NET showing how to catch both exception types using tab groups
• Lists affected System.Drawing APIs that use GDI+ internally
• Updated metadata to specify both C# and VB languages are covered

Updated main compatibility index: docs/core/compatibility/10.0.md

• Added entry to Windows Forms table in correct alphabetical order

Updated table of contents: docs/core/compatibility/toc.yml

• Added navigation entry under Windows Forms section

Background

GDI+ isn't particularly good at returning errors when it's unable to create internal objects. Many cases where object creation fails due to invalid input result in higher-level code getting a null and turning it into Status.OutOfMemory. This change to ExternalException provides more accurate error reporting since this exception type is already used in other System.Drawing code paths for similar GDI+ errors.

The documentation follows established patterns and includes proper cross-references, code examples in both languages, and comprehensive coverage of affected APIs.

Fixes #46057.

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Internal previews

📄 File	🔗 Preview link
docs/core/compatibility/10.0.md	Breaking changes in .NET 10
docs/core/compatibility/toc.yml	docs/core/compatibility/toc
docs/core/compatibility/windows-forms/10.0/system-drawing-outofmemory-externalexception.md	System.Drawing OutOfMemoryException changed to ExternalException

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PoliCheck Scan Report

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[learn-build-service-prod]

PoliCheck Scan Report

The following report lists PoliCheck issues in PR files. Before you merge the PR, you must fix all severity-1 issues. Other issues are also a high priority. The AI Review Details column lists suggestions for either removing or replacing the terms. If you find a false positive result, mention it in a PR comment and include this text: #policheck-false-positive. This feedback helps reduce false positives in future scans.

✅ No issues found

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[adegeo]

@gewarren This is ready